Store object to database

Hi,

I would like to save a object that I created to database.  I got this far looking at other solutions on EE (Save object in data base, Q_11075005).

I have created a Firebird database with two fields (Supplier_ID - Integer, sup_option - Binary BLOB).

The code below works not 100%.  In Button1Click I write my object to database.  The record is created and all looks good.  But when I read the blob field from DB to populate my user object (Button2Click) none of the properties of the object are set.

One thing I have noticed is that 'sizeof(usr)' (Button1Click) always returns 4, no matter how long I make my Fullname and Password properties.  Is this correct?  I guess this is my problem.  Only 4 bytes of my object are written to the DB.

procedure TForm_Main.Button1Click(Sender: TObject);
var
  usr : TSPLoginUser;
  bstream : TStream;
begin
  //The object that I would like to store in the DB
  usr := TSPLoginUser.Create;
  usr.Username := 'addey';
  usr.Fullname := 'Jacques';
  usr.Password := 'password';

  //Open query and create new record.
  dm.IBOQuery1.Open;
  dm.IBOQuery1.Append;
  dm.IBOQuery1SUPPLIER_ID.Value := 5;
  bstream := dm.iboQuery1.CreateBlobStream(dm.IBOQuery1SUP_OPTION,bmWrite);
  bstream.Write(usr,sizeof(usr));  //SizeOf(usr) always returns 4
  dm.IBOQuery1.Post;
  dm.IBOQuery1.Close;
end;

procedure TForm_Main.Button2Click(Sender: TObject);
var
  usr : TSPLoginUser;
  stream : TStream;
begin
  dm.IBOQuery1.Open;
  stream := dm.IBOQuery1.CreateBlobStream(dm.IBOQuery1SUP_OPTION,bmRead);
  stream.Read(usr,sizeof(usr));//After this none of the usr object's properties are set
  dm.IBOQuery1.Close;
end;

Thanks!